1. Field of the Invention
The present invention, in general relates to traffic lights and, more particularly, to devices that show the remaining time until a traffic light changes its signal.
Traffic lights are well known devices. Traffic lights that indicate the remaining time until a change occurs are also known to a limited degree. However, these prior devices fail to solve certain needs, and may even create new problems.
There is a need to indicate the remaining time until a traffic light changes its indication. If an approaching driver sees a red light, speeds up to it, stops abruptly, and then has the light turn green, he then accelerates briskly and drives off. This wastes energy.
If the driver instead knew that there were only 5 seconds remaining until it turned green he could, for example, take his foot off of the accelerator pedal and coast for a few seconds waiting for it to turn green, and then upon verifying that the intersection was indeed clear, begin to accelerate, or simply maintain speed. This would save energy.
However, there is a problem created by traffic lights that indicate the remaining time until the next signal change, that is from green to yellow, yellow to red, or red to green.
Traffic lights are color coded. Red means stop. Green means go and yellow means clear the intersection. As a result, drivers become habituated to certain colors and develop a strong association to the color that they see. The colors meaning certain things. They may in fact not fully notice the light itself, but rather possess an overall awareness of the color of the light that is before them and respond accordingly.
If a traffic light was, for example, to indicate the remaining time until the next signal change and do so with red numerals, then over time the driver would begin to falsely associate the color red with a go indication, rather than a stop indication. This would occur if, for example, the red numerals indicated that there were fifteen seconds of green (or go) time remaining. The driver would be exposed to contradictory visual data, seeing a green light and a red "15" seconds of time remaining in close proximity thereto.
As a result, a traffic light that counts down the time can result in desensitizing the driver to the color of the signal itself. It is not hard to understand how a desensitization to the color red can have highly deleterious effects, so much so that the various administrative agencies that select the kinds of traffic signals that are used would abstain from using such kinds of count-down devices, for fear of causing accidents.
Another problem with count-down types of traffic lights is that the duty cycle (i.e., the time the light is green as compared to red) will vary depending upon the time of day and traffic patterns. For example, a 30 second green period followed by a 30 second red period may be appropriate during normal times of the day for a particular intersection. However, during peak commuter times, a 45 second green and 15 second red time may be more appropriate.
A count-down light must be adaptable to function with such changes.
Another problem occurs with on-demand types of traffic lights that include a normal duty cycle but are able to override the normal duty cycle based on the immediate traffic flow. For example, if there are thirty seconds of green time remaining and there is no traffic passing through the intersection while cars are waiting at a red light to cross in a perpendicular direction, many modern traffic lights will detect this condition and curtail the thirty second countdown to only a few seconds before changing.
Obviously, a countdown indicator that is reading thirty seconds of green time remaining could mislead a motorist if is suddenly changed, without warning, to five seconds of remaining green time as a result of a change due to the demand pattern of the traffic.
Also, traffic lights, in general are subject to a supply of electrical power supplied by the local utility company. A disruption in electrical power causes traffic lights to cease to operate. This often occurs when the neighborhood is itself dark, as a result of the electrical power failure. It is desirable that traffic lights continue to function during such times so as to allow for the proper, controlled flow of traffic and also to foster feelings of safety among drivers and residents during power failures.
Accordingly there exists today a need for a traffic light that indicates the remaining time until a signal change is to occur, does not desensitize the driver to any particular color, is adaptable for use with variable duty cycle traffic lights, is adaptable for use with on-demand types of traffic lights, and is useful during power outages.
Clearly, such an apparatus would be a useful and desirable device.
2. Description of Prior Art
Traffic lights are, in general, known. For example, the following patents describe various types of these devices:
U.S. Pat. No. 3,234,506 to Hines, Feb. 8, 1966; PA1 U.S. Pat. No. 3,320,585 to Hines, May 16, 1967; PA1 U.S. Pat. No. 3,480,909 to Hines, Nov. 25, 1969; PA1 U.S. Pat. No. 5,150,116 to West, Sep. 22, 1992; PA1 U.S. Pat. No. 5,726,648 to Soon, Mar. 10, 1998; and PA1 U.S. Design Pat. No. 314,524 to Perry, Feb. 12, 1991.
While the structural arrangements of the above described devices, at first appearance, have similarities with the present invention, they differ in material respects. These differences, which will be described in more detail hereinafter, are essential for the effective use of the invention and which admit of the advantages that are not available with the prior devices.